1 //===- BranchProbability.h - Branch Probability Wrapper ---------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // Definition of BranchProbability shared by IR and Machine Instructions. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_SUPPORT_BRANCHPROBABILITY_H 15 #define LLVM_SUPPORT_BRANCHPROBABILITY_H 16 17 #include "llvm/Support/DataTypes.h" 18 #include <cassert> 19 20 namespace llvm { 21 22 class raw_ostream; 23 24 // This class represents Branch Probability as a non-negative fraction. 25 class BranchProbability { 26 // Numerator 27 uint32_t N; 28 29 // Denominator 30 uint32_t D; 31 32 public: 33 BranchProbability(uint32_t n, uint32_t d) : N(n), D(d) { 34 assert(d > 0 && "Denomiator cannot be 0!"); 35 assert(n <= d && "Probability cannot be bigger than 1!"); 36 } 37 38 static BranchProbability getZero() { return BranchProbability(0, 1); } 39 static BranchProbability getOne() { return BranchProbability(1, 1); } 40 41 uint32_t getNumerator() const { return N; } 42 uint32_t getDenominator() const { return D; } 43 44 // Return (1 - Probability). 45 BranchProbability getCompl() const { 46 return BranchProbability(D - N, D); 47 } 48 49 raw_ostream &print(raw_ostream &OS) const; 50 51 void dump() const; 52 53 /// \brief Scale a large integer. 54 /// 55 /// Scales \c Num. Guarantees full precision. Returns the floor of the 56 /// result. 57 /// 58 /// \return \c Num times \c this. 59 uint64_t scale(uint64_t Num) const; 60 61 /// \brief Scale a large integer by the inverse. 62 /// 63 /// Scales \c Num by the inverse of \c this. Guarantees full precision. 64 /// Returns the floor of the result. 65 /// 66 /// \return \c Num divided by \c this. 67 uint64_t scaleByInverse(uint64_t Num) const; 68 69 bool operator==(BranchProbability RHS) const { 70 return (uint64_t)N * RHS.D == (uint64_t)D * RHS.N; 71 } 72 bool operator!=(BranchProbability RHS) const { 73 return !(*this == RHS); 74 } 75 bool operator<(BranchProbability RHS) const { 76 return (uint64_t)N * RHS.D < (uint64_t)D * RHS.N; 77 } 78 bool operator>(BranchProbability RHS) const { return RHS < *this; } 79 bool operator<=(BranchProbability RHS) const { return !(RHS < *this); } 80 bool operator>=(BranchProbability RHS) const { return !(*this < RHS); } 81 }; 82 83 inline raw_ostream &operator<<(raw_ostream &OS, const BranchProbability &Prob) { 84 return Prob.print(OS); 85 } 86 87 } 88 89 #endif 90